(CNN)Eleven people were rescued on Thursday after their towing vessel — carrying 75,000 gallons of diesel fuel — sank off the coast of Oahu, according to Honolulu Coast Guard.
"Mayday, mayday, mayday." A radio recording released by the Coast Guard established the moment an officer sent a distress call to the base. "Approximately two and half miles west of Barbers Point Harbor," the officer said, "vessel appears to have started to sink."
The mayday call came after the pilot of the towing vessel Nalani called the Coast Guard at 3:13 p.m. HST to report their ship was flooding and could sink.
Two ships where in the vicinity and heard the distress call: the towing vessel Tiger 7 and a National Oceanic and Atmospheric Administration patrol boat. Both helped rescue the stranded crew members and as a result no injuries were reported, according to the Coast Guard.
The Nalani, a 95-foot towing vessel, carried 75,000 gallons of diesel fuel. The vessel sank in about 2,200 feet of water.
"A flight went up prior to sunset and observed a very light oil sheen approximately three miles long by 100 yards wide," said Coast Guard spokesman Darin McCracken.
"There is a very small trace amount of rainbow sheet. Most of it concentrated around the position of the vessel," he said.
The next assessment flight is scheduled for Friday morning.
The cause of the sinking remains under investigation and it is probable the vessel will not be recovered, said McCracken.
He said the fuel "most likely will naturally dissipate" but the full environmental impact has yet to be determined.